Single-rod measuring probes for electrochemical measurements are components of electrochemical measuring elements used in the field of sensor analysis. They are especially useful for determining pH and redox voltage. These measuring probes in most cases contain a reference electrode, which is installed in a cylindrical housing that is made of glass or plastic. In reference electrodes, an electrolyte solution, in most cases a KCL solution, has to be refilled intermittently with liquid electrolyte. When this is the case, the design of the refill opening causes problems.
Single-rod measuring probes are known which in the top of the electrodes have an axial hole with a circular cross-section for use as a refill channel, which channel can be sealed with a plug.
In the vast majority of the known single-rod measuring elements, the refill opening is made in the housing wall, i.e. in the electrolyte chamber wall, either directly as a hole or with an upstream radially-projecting nozzle or a laterally-projecting elevated refill olive, whereby both the opening and the nozzle or the olive have circular cross-sections and can be sealed with a plug or tube section.
The refill openings in the known single-rod measuring chains primarily have the drawback of awkward handling and/or inadequate tightness.
In several types, handling is made more difficult by accessories for filling the electrode housing; however, such accessories are not always available. In other types, sealing devices are provided that are difficult to handle or are inadequate.
A more general drawback of the known measuring elements with refill openings having circular cross-sections is that during refilling, electrolyte is spilled since the air in the electrolyte space cannot escape (bubble-free).